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奇怪的测试行为。我有生成随机值的类。

std::random_device RandomProvider::rd;
std::mt19937 RandomProvider::rnb(RandomProvider::rd());
    #define mainDataType unsigned int

mainDataType RandomProvider::GetNextValue(mainDataType upperLimit)
{
    static std::uniform_int_distribution<int> uniform_dist(1, upperLimit);
    return uniform_dist(rnb);
}

并进行单元测试以测试其行为。

    TEST_METHOD(TestRandomNumber)
    {
        CreateOper(RandomNumber);
        int one = 0, two = 0, three = 0, unlim = 0;
        const int cycles = 10000;

        for (int i = 0; i < cycles; i++)
        {
            mainDataType res = RandomProvider::GetNextValue(3);
            if (res == 1) one++;
            if (res == 2) two++;
            if (res == 3) three++;
        }

        double onePerc = one / (double)cycles;
        double twoPerc = two / (double)cycles;
        double threePerc = three / (double)cycles;

        Assert::IsTrue(onePerc > 0.20 && onePerc < 0.40);
        Assert::IsTrue(twoPerc > 0.20 && twoPerc < 0.40);
        Assert::IsTrue(threePerc > 0.20 && threePerc < 0.40);
    }

测试在调试中一直通过，如果我选择它并只运行它。但是当我与其他测试一起运行它时，它总是失败。我将调试输出添加到文本文件并得到虚幻值 onePerc = 0.0556、twoPerc = 0.0474 和threePerc = 0.0526...这是怎么回事？（我正在使用 VS2013 RC）

4

1 回答 1

1

Since you use a static uniform_int_distribution the first time you call GetNextValue the max limit is set, never being changed in any subsequent call. Presumably in the test case you mentioned, your first call to GetNextValue had a different value than 3. Judging from the values returned it looks like probably either 19 or 20 was used in the first such call.

于 2013-10-01T16:52:26.910 回答